We propose to continue our studies in modern liquid chromatography and to develop tools that can be applied to the separation of biochemically and clinically important mixtures. We have three main programs that we shall pursue - (a) development of high selectivity using chemically bonded reversed phases; (b) high performance separation of peptides; and (c) high performance separation of proteins. In the reversed phase area we shall be particularly interested in the role of the mobile phase, particularly ternary mixed phases, on the separation of polar and ionic species. The role of temperature and unreacted silanol groups will also be carefully elucidated. In the peptide area, we shall try to develop separation fundamentals for small peptides on reversed phase materials. The role of pH, ionic strength, and added metal ion will be particularly examined. We shall use this expertise in the separation of chemically modified peptides and ultimately in examining peptide hormones via trace analysis techniques. In the protein area, we shall study the development silica-based phases that have been modified for exclusion, ion exchange and hydrophobic chromatography. Such phases will employ particle sizes under 5 micron m for high performance separations. These phases will be applied in several areas including separation of isoenzymes, determination of molecular weight and preparative scale purification of proteins.